Accession Number : ADA257722
Title : DARPA/ONR Quarterly Report.
Descriptive Note : Rept. for 1 Jul-30 Sep 1992,
Corporate Author : DUKE UNIV DURHAM NC
Personal Author(s) : Reif, John H
Report Date : 30 Sep 1992
Pagination or Media Count : 13
Abstract : Consider an array of Processing Elements (PEs), connected by a 2- dimensional grid network, and holding at most one operand of an expression in each PE. Suppose that each PE is allowed, in any one parallel step, to receive one item of data from any of its 4 immediate neighbors, and to transmit one datum, as well. How can an associative operator, such as addition, combine all the operands, using as little time for communication as possible? An expression using such a single operator is termed a uniform expression. When the total number of communication links used is the measure of goodness, this problem becomes a Steiner Tree problem, in the Manhattan Distance metric. When the measure is minimizing the parallel time to completion, a method for solving this problem is given which is optimal to within an additive constant of 2 time- steps. The method has applications when the operands are matrices, spread over an array of PEUs, as well. Some lower bounds for this problem, in more general networks, are also proven.
Descriptors : *ALGORITHMS , *PARALLEL PROCESSING , NETWORKS , PROCESSING , TIME , INSTALLATION , ADDITIVES , UNIFORMS , ADDITION , NUMBERS , CONSTANTS , TREES , GRIDS , ARRAYS , COMPUTER ARCHITECTURE
Subject Categories : Computer Hardware
Distribution Statement : APPROVED FOR PUBLIC RELEASE